Recurrent deletions of chromosome 9p21.3 encompassing the cell cycle regulatory genes CDKN2A/B were found in all tumors, corroborating previous karyotypic and molecular cytogenetic findings that led to the notion that chordomas might be amenable to CDK4/6 inhibition13, a hypothesis that is being explored in a phase 2 clinical trial (ClinicalTrials.gov Identifier NCT03110744). Here, CDK4 is linked to chordoma.